The preferred embodiment relates generally to an apparatus for actuating couplers that engage gears in a transmission.
A twin clutch transmission must have some mechanism to move shift forks to engage gears. Shift drums convert rotary motion of a drum into appropriate linear motion of a set of shift forks. For optimal shift flexibility, it is best to have separate control of the engagement of the odd-numbered gears and the even-numbered gears. However, it is also advantageous to locate the shift drum physically close to the shift forks. Unfortunately, odd and even gears tend to be located at opposite ends of the gearbox, with both odd and even gears along each side. For example, the first, second and sixth gears may be located on one side of the gearbox, and the third, fourth, and fifth, and reverse gears are located on the opposite side.
It is feasible to use one electric motor to engage and disengage gears one, two and six and to use another electric motor to engage and disengage gears three, four, five and reverse. But complex mechanisms are required in order to enable three gear step shifts, i.e., six-three, five-two downshifts, with that arrangement. These complex mechanisms introduce potential failure modes. Also, these arrangements require an additional interlock mechanism to preclude simultaneous engagement of multiple odd gears or multiple even gears.